const config = require('../../../config');

// Test if potential opening or closing delimieter
// Assumes that there is a "$" at state.src[pos]
function isValidDelim(state, pos) {
    var prevChar;
    var nextChar;
    var max = state.posMax;
    var can_open = true;
    var can_close = true;
    prevChar = pos > 0 ? state.src.charCodeAt(pos - 1) : -1;
    nextChar = pos + 1 <= max ? state.src.charCodeAt(pos + 1) : -1;

    // Check non-whitespace conditions for opening and closing, and
    // check that closing delimeter isn't followed by a number
    if (prevChar === 32 /* " " */ || prevChar === 9 /* \t */ || (nextChar >= 48 /* "0" */ && nextChar <= 57) /* "9" */) {
        can_close = false;
    }
    if (nextChar === 32 /* " " */ || nextChar === 9 /* \t */) {
        can_open = false;
    }
    return {
        can_open: can_open,
        can_close: can_close
    };
}
function math_inline(state, silent) {
    var start;
    var match;
    var token;
    var res;
    var pos;
    var esc_count;
    if (state.src[state.pos] !== '$') {
        return false;
    }
    res = isValidDelim(state, state.pos);
    if (!res.can_open) {
        if (!silent) {
            state.pending += '$';
        }
        state.pos += 1;
        return true;
    }

    // First check for and bypass all properly escaped delimieters
    // This loop will assume that the first leading backtick can not
    // be the first character in state.src, which is known since
    // we have found an opening delimieter already.
    start = state.pos + 1;
    match = start;
    while ((match = state.src.indexOf('$', match)) !== -1) {
        // Found potential $, look for escapes, pos will point to
        // first non escape when complete
        pos = match - 1;
        while (state.src[pos] === '\\') {
            pos -= 1;
        }

        // Even number of escapes, potential closing delimiter found
        if ((match - pos) % 2 == 1) {
            break;
        }
        match += 1;
    }

    // No closing delimter found.  Consume $ and continue.
    if (match === -1) {
        if (!silent) {
            state.pending += '$';
        }
        state.pos = start;
        return true;
    }

    // Check if we have empty content, ie: $$.  Do not parse.
    if (match - start === 0) {
        if (!silent) {
            state.pending += '$$';
        }
        state.pos = start + 1;
        return true;
    }

    // Check for valid closing delimiter
    res = isValidDelim(state, match);
    if (!res.can_close) {
        if (!silent) {
            state.pending += '$';
        }
        state.pos = start;
        return true;
    }
    if (!silent) {
        token = state.push('math_inline', 'math', 0);
        token.markup = '$';
        token.content = state.src.slice(start, match);
    }
    state.pos = match + 1;
    return true;
}
function math_block(state, start, end, silent) {
    var firstLine;
    var lastLine;
    var next;
    var lastPos;
    var found = false;
    var token;
    var pos = state.bMarks[start] + state.tShift[start];
    var max = state.eMarks[start];
    if (pos + 2 > max) {
        return false;
    }
    if (state.src.slice(pos, pos + 2) !== '$$') {
        return false;
    }
    pos += 2;
    firstLine = state.src.slice(pos, max);
    if (silent) {
        return true;
    }
    if (firstLine.trim().slice(-2) === '$$') {
        // Single line expression
        firstLine = firstLine.trim().slice(0, -2);
        found = true;
    }
    for (next = start; !found; ) {
        next++;
        if (next >= end) {
            break;
        }
        pos = state.bMarks[next] + state.tShift[next];
        max = state.eMarks[next];
        if (pos < max && state.tShift[next] < state.blkIndent) {
            // non-empty line with negative indent should stop the list:
            break;
        }
        if (state.src.slice(pos, max).trim().slice(-2) === '$$') {
            lastPos = state.src.slice(0, max).lastIndexOf('$$');
            lastLine = state.src.slice(pos, lastPos);
            found = true;
        }
    }
    state.line = next + 1;
    token = state.push('math_block', 'math', 0);
    token.block = true;
    token.content =
        (firstLine && firstLine.trim() ? firstLine + '\n' : '') + state.getLines(start + 1, next, state.tShift[start], true) + (lastLine && lastLine.trim() ? lastLine : '');
    token.map = [start, state.line];
    token.markup = '$$';
    return true;
}
module.exports = (md) => {
    var inlineRenderer = function (tokens, idx) {
        return `<latex value="${encodeURIComponent(tokens[idx].content).replace(/'/g, '%27')}" type="line"></latex>`;
    };
    var blockRenderer = function (tokens, idx) {
        return `<latex value="${encodeURIComponent(tokens[idx].content).replace(/'/g, '%27')}" type="block"></latex>`;
    };
    md.inline.ruler.after('escape', 'math_inline', math_inline);
    md.block.ruler.after('blockquote', 'math_block', math_block, {
        alt: ['paragraph', 'reference', 'blockquote', 'list']
    });
    md.renderer.rules.math_inline = inlineRenderer;
    md.renderer.rules.math_block = blockRenderer;
};
